Hiccup - Causes of hiccups

Hiccups occur when your diaphragm (the thin layer of muscle that separates your chest cavity from your abdomen) suddenly and involuntarily contracts (tightens).

As your diaphragm contracts, it causes you to breathe in air very quickly. The incoming air is stopped when your glottis (the opening between your vocal cords) closes suddenly, producing the characteristic sound of a hiccup.

Short-term hiccups

Most cases of hiccups occur for no apparent reason. Everyone experiences a short bout of hiccups from time to time. This is perfectly normal and nothing to be concerned about.

The most common causes of short-term hiccups are:

• consuming large amounts of alcohol
• excessive smoking
• a bloated stomach – usually as a result of eating or drinking too quickly
• a sudden change in room temperature
• a sudden change in the temperature inside your stomach

Sometimes, short-term hiccups may also occur as a result of:

• shock
• stress – the feeling of being under pressure
• excitement

See below for more information about psychological factors that can cause hiccups.

People experiencing short-term hiccups usually get better without the need for treatment.

Long-lasting hiccups

In rare cases, persistent and intractable hiccups can be caused by a more serious underlying condition, such as gastro-oesophageal reflux disease (GORD) (see below). However, in other cases the cause of hiccups remains unknown (idiopathic).

Several conditions can cause hiccups. However, even with testing and investigation an underlying cause can sometimes not be identified.

Possible underlying conditions

Some of the conditions that can cause long-term hiccups include:

• gastrointestinal conditions – such as gastro-oesophageal reflux disease (GORD), inflammatory bowel disease (IBD) or a small bowel obstruction
• respiratory conditions – such as asthma, pneumonia or pleurisy
• conditions affecting the central nervous system – such as stroke, a tumour affecting the brain, encephalitis or a traumatic brain injury
• a condition causing irritation of the vagus nerve (which could disrupt nerve signals in your body) – such as goitre, pharyngitis or meningitis
• a psychological reaction – such as shock, fear, grief, excitement, hysterical behaviour, anxiety or stress
• conditions affecting your metabolism (the way your body digests food) – such as diabetes, hypoglycaemia or hyperglycaemia

Medication

Persistent hiccups can sometimes be caused by a reaction to certain types of  medication. For example:

• anaesthesia – medication given before a surgical operation or procedure that causes a loss of sensation 
• corticosteroids – medication that reduces inflammation (swelling)
• benzodiazepines – a type of sedative that helps to reduce anxiety
• barbiturates – a type of sedative sometimes used to prevent seizures (fits)
• opioids – medication used to treat pain; morphine and methadone are both strong opioids
• methyldopa – medication used to treat high blood pressure (hypertension)

Possible complications

Prolonged hiccups can sometimes cause a number of complications. For example, in some cases it can lead to:

• insomnia 
• weight loss, due to difficulty eating
• exhaustion
• depression 

Visit your GP or another healthcare professional if you have hiccups that have lasted longer than 48 hours and you are unsure about what is causing them.

Read more about how hiccups are diagnosed.